Magnetic t square and drafting board



Sept. 18, 1951 L. F. wlcKMAN 2,568,575

MAGNETIC T SQUARE AND DRAFTING BOARD Filed Oct. 24, 1949 2 Sheets-Sheet 1 L WU/bmm INVENTOR l l BY l f l 1 ATTORNEYS.

Sept. 18, 1951 L. F. wlcKMAN MAGNETIC T SQUARE AND DRAFTING BOARD 2 Sheets-Sheet 2 Filed oct. 24, 1949 INVENTOR ATTORNEYS Patented Sept. 1.8,K 1951 UNITED STATES PATENT OFFICE MAGNETIC T SQUARE AND DRAFTIN G BOARD 1 Claim.

This invention relates to T-square construction for use in connection with drawing or drafting boards.

The primary object of the invention is to provide means for attracting and holding the head of a T-square against the guiding edge of a drawing board, thereby insuring a straight or perpendicular edge at all times, when the T-square assembly is being moved from the bottom edge of the drafting or drawing board, to the top edge thereof, or vice versa.

An important object of the invention is to provide means for insuring a uniform contact between the head of the T-square and drawing board at all times, without the necessity of the draftsman or person using the T-square, applying physical force to maintain a true contact throughout the length of the straight edge of the T-square head and the edge of the drawing board.

With the foregoing and other objects in View which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts, hereinafter more fully described and pointed out in the claim, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

Referring to the drawings:

Figure 1 is a fragmental elevational view of a drawing board, illustrating a T-square, constructed in accordance with the invention, as positioned thereon.

Fig. 2 is a rear elevational view of the T-square and one edge of the drawing board.

Fig. 3 is a sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is a plan view illustrating the head of a T-square as equipped with a modied form of the invention.

Fig. 5 is a fragmental perspective view wherein one of the poles of the magnet is illustrated in block form.

Fig. 6 is a plan view wherein is shown the use of electro-magnets on a T-square head.

Fig. 'l is a diagram illustrating the circuits of the electro-magnet.

Referring to the drawing in detail, the reference character 5 indicates a drawing or drafting board, which is provided with a steel bar or armature Ii secured along one edge of the drafting board, as by means of the screws l, that pass through the flange 8 which fits against the bottom of the drafting board adjacent to the edge thereof.

The reference character 9 indicates a T-square which is provided with the usual head I3 that contacts one edge of a drawing board when in use.

Secured to the inner edge of the head I0 is a magnet which comprises the bar II, the ends of which terminate adjacent to the ends of the head It). Pivotally mounted on the bar I I adjacent to the ends thereof, are the rollers I2, the ends of the bar I I being curved downwardly and inwardly towards each other so that the rollers I 2 will contact the armature 6 at a point intermediate the upper and lower edges of the armature 6. the rollers embody high coercive force permanent magnets, one roller constituting the north pole of the magnet, while the other roller constitutes the south pole, to the end that. the head of the T-square supporting the magnet will be drawn into close engagement with the armature 6, as the head is moved to bring the magnet into close contact with the edge of the drawing board.

This structure constitutes one which may be readily and easily applied to the usual drawing board and T-square, making use of permanent magnets as a means for holding a T-square in position against a drawing board.

In the form of the invention as shown by Fig. 4 of the drawings, the head I3 of this T-square, is provided with the magnet including a bar I4, block I5 formed integral with the bar and eX- tending forwardly from one edge of the bar, and the block I6 which extends forwardly from the opposite end of the bar, the block I 5 constituting the north pole of the magnet, while the block I6 constitutes the south pole of the magnet. This magnet cooperates with the steel bar I'I that is secured along one edge of the drafting board, indicated by the reference character I8.

In Fig. 6 of the drawing I have provided electromagnets I9 and 20 which are disposed adjacent to the ends of the straight edge of the head 2I of this T-square, the electro-magnets I9 and 2D being in circuit with the source of electricity supply 22, which may be in the form of a battery, or the device may be plugged into the usual electric house circuit, through the wires 23 and 24, there being provided a switch 25 for controlling the circuit to the electro-magnets.

These electro-magnets cooperate with the steel bar 26 which is secured along one edge of the drawing board, and acts as the armature to cause the T-square to be attracted to the edge of the drawing board when the electric current is applied to the magnets.

From the foregoing it will be seen that due to the construction shown and described, I have provided an attachment which may be used in connection with T-squares and drawing boards, for holding a T-square into close engagement with one edge of a drawing board to insure a straight or perpendicular edge at all times when moving the T-square assembly along one edge of a drawing board.

Having thus described the invention, what is Claimed is:

The combination with a drawing board having an armature secured along a longitudinal edge thereof, of a T-square having a head providing a straight edge, a permanent magnet comprising a bar secured to the head of the T-square, the ends of the bar being curved downwardly and inwardly, magnet pole members embodying rollers secured to the downwardly and inwardly curved ends of the bar, cooperating with -the armature in holding the head of the T-square to one edge of the drawing board.

LESTER F. WICKMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date VRe.11,189 Carr Sept. 15, 1891 926,247 Draper June 29, 1909 2,420,090 Nelsion May 6, 1947 FOREIGN PATENTS Number Country Date 15,657 Germany 1-- Oct. 13, 1881 Switzerland July 2, 1928 

